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361.
重金属的生物毒性不仅与其总量有关.更大程度上由其形态分布所决定,不同的形态产生不同的环境效应。为了解城市大气降尘中的镉污染,采用Tessier连续提取法对成都经济生态区内不同区域的24个大气降尘样中镉的赋存形态进行了研究。结果表明,大气降尘中的镉主要以残留态存在;各形态镉在总镉中所占的平均百分比含量的排列顺序依次为:残留态〉碳酸盐结合态〉交换态〉铁锰结合态〉有机结合态(78.907%、8.917%.6.420%、3.419%、2.365%);交换态镉、碳酸盐结合态镉具有较高生物有效性,铁锰氧化物结合态.有机结合态、残留态这3种形态镉的生物有效性很低。分析得出:汽油和煤的燃烧,以及工厂排放镉能加大城市大气降尘的镉污染。 相似文献
362.
A CGA→TGA mutation at codon 111 in exon 3 of the phenylalanine hydroxylase (PAH) gene was recently identified in a Chinese phenylketonuria (PKU) patient. This paper reports the prenatal diagnosis of a Chinese fetus at risk for PKU using DNA amplification with PCR and oligonucleotide hybridization. RFLP analysis revealed that the fetus had inherited a PKU gene from his mother, but his paternal PAH gene was uninformative. PCR amplification of 300 bp which included exon 3 plus the flanking intronic sequences of the PAH gene was performed. The amplified DNA was hybridized with a pair of allele-specific oligonucleotide probes. The results indicated that the fetal DNA carried a PAH 111 Arg→Ter mutant gene inherited from his father. Thus, the fetus was predicted to be affected with PKU. 相似文献
363.
环保资产评估是石化企业资产评估的重要组成部分,涉及资产所有者、经营者和使用者的合法权益,应当加以关注。借鉴现有资产评估的方法,提出了企业资产交易活动中有关环保资产评估的几个基本概念、主要内容、原则、范围、方法和标准,并做了简要说明。 相似文献
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A synergetic model for implementing an integrated management system: an empirical study in China 总被引:4,自引:0,他引:4
The implementation and certification of quality, environmental and occupational health and safety management systems have become a priority for many organizations. They are viewed as symbol for success and prerequisite for survival. However, it has been proved to be difficult to operate multiple parallel management systems covering quality, environment, and occupational health and safety and to ensure their alignment with the organization's strategy. To investigate the current status of integrated management system (IMS), a structured questionnaire survey was administrated. It is concluded that the major problems for enterprises to operate multiple parallel management systems include: it causes complexity of internal management, it lowers management efficiency, it incurs cultural incompatibility, it causes employee hostility, and increases management costs. The survey also examined the internal and external factors that affect the implementation of IMS. The internal factors include: (1) human resources, (2) organizational structure, (3) company culture, and (4) understanding and perception. The external factors consist of: (1) technical guidance, (2) certification bodies, (3) stakeholders and customers, and (4) the institutional environment. The article proposes a multi-level synergy model (strategic synergy, organizational structural-resource-cultural synergy, and documentation synergy) for an effective implementation of IMS. 相似文献
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368.
地下水中汞的形成及其与人群健康的关系 总被引:1,自引:0,他引:1
地下水中汞元素的形成,主要是含汞矿物岩土溶解作用的结果,但其含量一般很低。汞与人体关系密切,结肠癌、肺癌死亡率与土壤中汞含量呈正相关,胃癌死亡率则与汞元素含量呈负相关。地下水汞元素含量小于1μg/L时,不会对人体健康产生危害。 相似文献
369.
Ten male buffalo calves were randomly allotted into five groups of two each. Four groups were fed with cadmium, molybdenum, cadmium-molybdenum, and copper-cadmium-molybdenum respectively for 130 days to determine the elements' metabolic interactions in calves. These results indicated that cadmium and molybdenum could increase the accumulation of molybdenum and cadmium in liver and kidneys in buffalo calves, but copper could not. reduce to normal the levels of molybdenum and cadmium in liver and kidneys caused by cadmium-molybdenum. In addition, we found the copper concentrations in liver and kindeys was significantly greater in treatment calves than in controls. 相似文献
370.
在采用分光光度法对氰化物的测定中,有些问题尚无明确的记载和经验.例如:显色液的有效时间;样品显色后最佳测定时间;样品馏出液可放置时间.本文在大量实验的基础上针对上述问题进行了探讨分析.此外又论述了方法的某些进展.这些内容对于氰化物的分析测定具有一定的实用价值. 相似文献